Among the German auto makers releasing sales figures this week was Audi. The company, the luxury arm of Volkswagen AG, reported a 16% increase in January sales globally and 7.5% sales rise in the U.S., where it plans to introduce four new diesel-fueled models by year-end.

The diesel models, Audi hopes, will help increase its U.S. footprint.

But it’s a tough sell. Diesel faces a pernicious PR problem in the U.S. Say “diesel” to many car shoppers, and they envision loud cars burping stinky exhaust smoke.

In an effort to rebrand diesel and stoke interest in new cleaner-burning diesel car models, Audi recently banded together with other German auto makers and suppliers to launch a website called www.clearlybetterdiesel.org.

As weak U.S. gas prices drag down its earnings, Royal Dutch Shell is planning to bolster its profits by converting natural gas into road fuels like diesel, which it can sell at much higher prices.

Many energy companies are seeking to capitalize on low U.S. natural gas prices by exporting the fuel to Asia or Europe or burning it directly in specially converted trucks or buses.

But only Shell can leverage its position as the world’s number one producer of gas-to-liquid fuels, which can fill the tank of any car, to tap an even more profitable opportunity in the domestic U.S. fuel market.

The move could be a smart one as it avoids the need for politically contentious export permits, but the process is still likely to be slow and complex.

It’s also more capital intensive than investing in the liquefied natural gas infrastructure that is required for exports.

The vote by U.K. fuel tanker drivers to go ahead with a strike for improving working conditions could be bad news for drivers paying already sky-high gasoline and diesel prices in the U.K., even if the strike doesn’t go through.

The Automobile Association said gasoline retailers could raise their prices by as much as 2 or 3 pence if the potential strike triggers panic among U.K. drivers. While this doesn’t sound like a lot, as diesel and gasoline prices in the U.K. are already at record highs, with both products hitting new records most days this month.